Test Circuitry and Techniques for Logic Tiles of FPGA

ABSTRACT

An integrated circuit comprising a field programmable gate array including a plurality of logic tiles, wherein, during operation, each logic tile is configurable to connect with at least one other logic tile, and wherein each logic tile includes: (1) a normal operating mode and test mode, (2) an interconnect network including a plurality of multiplexers, wherein during operation, the interconnect network of each logic tile is configurable to connect with the interconnect network of at least one other logic tile in the normal operating mode and (3) bitcells to store data. The FPGA also includes control circuitry, electrically connected to each logic tile, to configure each logic tile in a test mode and enable concurrently writing configuration test data into each logic tile of the plurality of logic tiles when the FPGA is in the test mode.

RELATED APPLICATION

This application is a divisional of U.S. Non-Provisional applicationSer. No. 16/186,882, filed Nov. 12, 2018 (still pending). Thisapplication and the '882 application claim priority to and the benefitof U.S. Provisional Application No. 62/585,677, entitled “Test Circuitryand Techniques for Logic Tiles of FPGA”, filed Nov. 14, 2017. The '677provisional application is hereby incorporated herein by reference inits entirety.

INTRODUCTION

There are many inventions described and illustrated herein. In oneaspect, the present inventions are directed to circuitry and techniquesfor testing, in parallel, a plurality of logic tiles of an integratedcircuit. The logic tiles may be a field programmable gate array (FPGA,e.g., an embedded FPGA) disposed in or on the integrated circuit whereinthe FPGA includes programmable/configurable logic circuitry having aplurality of tiles (e.g., arranged in an array of row(s) and column(s))wherein one or more (or all) tiles includes programmable components(“tiles” are often called “configurable logic blocks” (CLB), “logicarray blocks” (LAB), or “logic tiles”—hereinafter collectively “logictiles”).

In addition thereto, or in lieu thereof, in another aspect, the presentinventions are directed to circuitry and techniques for writing orloading, in parallel, configuration data (e.g., test mode configurationdata) into a plurality of logic tiles of an integrated circuit to testthe functionality and/or operability of the circuitry in/of each of thelogic tiles. In one embodiment, the testing of circuitry of the logictiles may be implemented in parallel wherein circuitry of each of aplurality of or all logic tiles are tested or undergo one or more testsequences concurrently (i.e., at the same time) in a testprocess/sequence of the programmable/configurable logic circuitry.Alternatively, such testing of circuitry of the plurality of logic tilesmay be implemented serially wherein the circuitry of each logic tile oreach group of logic tiles of the programmable/configurable logiccircuitry are tested or undergo one or more test sequences at differenttimes in the test process/sequence (e.g., separately and/or sequentiallyfrom the other logic tiles and/or groups of logic tiles of theprogrammable/configurable logic circuitry). Notably, the presentinventions may implement any test sequence/process and/or test data/testmode configuration data now known or later developed; all of which areintended to fall within the scope of the present inventions.

In one embodiment, circuitry of the logic tiles may be “isolated” orelectrically disconnected from circuitry of other logic tiles (e.g.,circuitry of adjacent logic tiles) and/or circuitry external to theprogrammable/configurable logic circuitry. Here, the circuitry of alogic tile under test is electrically “isolated” from circuitryconnected thereto during normal or typical operation in order to isolateand more readily determine whether circuitry of the logic tile undertest is inoperative, faulty, non-functional and/or unreliable. In testmode, selected interconnects and/or inputs/outputs of the logic tile maybe communicatively and/or electrically “disconnected” or “disabled” fromthe associated interconnects, circuitry and/or input/output of otherlogic tiles or external circuitry connected thereto.

For example, the interconnect network or circuitry of the interconnectnetwork of a logic tile may be tested in isolation whereby suchcircuitry is effectively disconnected from interconnect network(s) ofother logic tiles. In this way, one or more test sequences may beimplemented with respect to the circuitry of the interconnect network ofa logic tile and the results thereof more readily determine orcharacterize the integrity, operability and/or reliability of thecircuitry of the logic tile(s) under test. In one embodiment, isolationcircuitry may be employed to disconnect or disable selectedinterconnects of one or more stages of the interconnect network fromstages of one or more associated interconnect network of other logictile(s) (e.g., adjacent logic tile(s)) of the programmable/configurablelogic circuitry. For example, the output(s) of interconnects of one ormore stages of the interconnect network of the logic tile under test orundergoing a test sequence that connect to an associated interconnectnetwork of other logic tile(s) during normal operation are looped backinto the interconnect network of such logic tile during performance of atest sequence/process of the logic tile (e.g., a test sequencepertaining to the interconnect network). Any other I/Os that connectsbetween two or more (or all) logic tiles in functional or normal modemaybe disconnected and looped back in the same or a similar manner tothe interconnect network and RBB I/O logic described herein. In thisway, the impact of the operability or functionality of circuitry ofother logic tile(s) (e.g., adjacent logic tile(s)) is managed, limitedand/or eliminated relative to the testing of circuitry of the logic tileunder test.

Notably, the isolation circuitry may be employed in the test mode and ina non-test mode (i.e., during normal operation) in order to disconnectcertain circuitry from circuitry of other logic tiles to which is ittypically connected during normal operation (i.e., when the logic tileis programmed with normal configuration data for a normalconfiguration). That is, the isolation circuitry may be enabled when alogic tile is in a functional or normal mode wherein, the interconnectnetwork (circuitry associated with the interconnect network), of a logictile for example, may be isolated or disconnected from the interconnectnetwork(s) of one or more (or all) of the other logic tiles (e.g., oneor more (or all) of the neighboring or adjacent logic tiles).

In one embodiment, test mode control circuitry (which, for example, isdisposed in/on the integrated circuit) may be employed to program orconfigure circuitry (e.g., multiplexers), input/output (I/O) and/or theswitch interconnect network of the logic tile(s) to program and/orconfigure one or more (or all) logic tiles into a test mode or test modeconfiguration. For example, the test mode control circuitry may issueone or more control signals to circuitry of the logic tiles to, forexample, implement or enable (i) writing or loading of test modeconfiguration data to or into a plurality (or all) of the logic tiles inparallel or sequentially, and/or (ii) testing of circuitry in aplurality (or all) of the logic tiles in parallel or sequentially (e.g.,using the test mode configuration data), and/or (iii) isolationcircuitry in one or more (or all) of the logic tiles to disconnectcircuitry of a logic tile from circuitry of other logic tiles (e.g.,circuitry of adjacent logic tile(s) that is connected during normaloperation) when testing of circuitry of the logic tile at issue (i.e.,under test).

Moreover, the test mode control circuitry may also enable or facilitateread-back of the test data/configuration after one or more logic tilesare programmed, configured or written with test data (e.g., prior to orafter implementation of the test sequence). The read-back operation maybe employed to verify a test mode configuration(s) and/or test datawritten to or loaded into such logic tile(s). In addition thereto, or inlieu thereof, the read-back operation may access the data of testresults in order to assess the integrity, operability or functionalityof the circuitry under test (e.g., in each of the logic tiles). In oneembodiment, the read-back operation may employ the configuration port toread the test data/configuration previously written into the logictile(s)—for example, via parallel writing or loading of test modeconfiguration data to or into a plurality (or all) of the logic tiles ofthe programmable/configurable logic circuitry.

Notably, the test mode control circuitry may program or configure one ormore (or all) logic tiles during a test sequence which may be performedwhen the IC is engaged or connected to IC test equipment/tools and/or,for example, at initialization or at start-up of the integrated circuitand/or FPGA.

Briefly, an exemplary FPGA includes control circuitry, timing or clockcircuitry, power supply circuitry and programmable/configurable logiccircuitry. (See, FIG. 1A). Each logic tile of the array or plurality oflogic tiles of the programmable/configurable logic circuitry includeslogic transistors (that may be interconnected, for example, asmultiplexers having two or more inputs which are electricallyinterconnected into a network as well as connected to, for example,associated data storage elements, input pins and/or look-up tables(LUTs) that, when programmed, determine the operation of themultiplexers).

The plurality of logic tiles of an exemplary embodiment ofprogrammable/configurable logic circuitry, for example, of an FPGA,includes input/output of the logic tiles which facilitates communicationbetween the logic tiles and/or between one or more logic tiles andcircuitry external to the programmable/configurable logic circuitry.(See, FIG. 1B). For example, in one embodiment, each logic tile mayinclude Logic-Memory and/or DSP cores and contain more than a thousandLUTs (e.g., 6-input LUTs) from hundreds of Reconfigurable BuildingBlocks (RBBs), including Kb RAM, and hundreds of I/O blocks (e.g.,2-input, 2-output each). As noted above, the logic tiles may be “tiled”to form an array from the LUTs and from the DSP multiply and accumulateblocks (MACs).

An FPGA may be configured and/or reconfigured (hereinafter, unlessstated otherwise, collectively “configured” or the like (e.g.,“configure”, “configuring” and “configurable”)) by a user, customerand/or a designer before and/or after manufacture. The FPGA includes,among other things, a plurality of logic tiles wherein each logic tileincludes a logic tile interconnect network of configurable interconnectsthat facilitate communication within the logic tile. (See, e.g., FIGS.1A and 1B). One or more (or all) of the logic tiles include a pluralityof multiplexers which are electrically interconnected into a network(for example, a hierarchical network and/or mesh network).

In addition, the FPGA includes tile-to-tile interconnects thatinterconnect the logic tile interconnect network of each logic tilethereby providing communication between the logic tiles. (See, e.g.,FIG. 1C). (See, Provisional Patent Application No. 62/735,988 (which isincorporated herein by reference). The logic tile interconnect networkof each logic tile may include a plurality of switch matrices (e.g., anM×N switch matrix) arranged in a plurality of switch matrix stages orswitch matrices stages which are interconnected into a logic tileinterconnect network via logic tile interconnects. (See, for example,FIG. 1D—see also, for example, the interconnect networks describedand/or illustrated in U.S. Pat. No. 9,503,092, which are incorporatedherein by reference). As such, logic tiles are configurable tocommunicate, during operation of the integrated circuit, betweencomputing elements within the logic tile as well as with at least oneother logic tile of the FPGA.

With reference to FIGS. 1C and 1D, in one embodiment, the tile-to-tileinterconnects of the mesh-type tile-to-tile interconnect network connectthe highest stage of the logic tile interconnect network of each logictile. In another embodiment, the tile-to-tile interconnects of themesh-type tile-to-tile interconnect network connect an intermediatestage of the logic tile interconnect network of each logic tile. Indeed,in one embodiment, the tile-to-tile interconnects of the mesh-typetile-to-tile interconnect network may directly interconnect a pluralityof stages of the logic tile interconnect network wherein thetile-to-tile interconnects directly connect to a plurality of stages ofeach logic tile interconnect network of logic tiles—thereby directlyinterconnecting two or more stages of logic tile interconnect network ofeach logic tile wherein each stage is directly connected into a separateand distinct mesh-type tile-to-tile interconnect network.

Notably, the integrated circuit may be, for example, a processor,controller, state machine, gate array, system-on-chip (SOC),programmable gate array (PGA) and/or FPGA.

There are many inventions described and illustrated herein. The presentinventions are neither limited to any single aspect nor embodimentthereof, nor to any combinations and/or permutations of such aspectsand/or embodiments. Moreover, each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, certainpermutations and combinations are not discussed and/or illustratedseparately herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventions may be implemented in connection with embodimentsillustrated in the attached drawings. These drawings show differentaspects of the present inventions and, where appropriate, referencenumerals or names identifying or illustrating like structures,components, materials and/or elements in different figures are labeledsimilarly. It is understood that various combinations of the structures,components, materials and/or elements, other than those specificallyshown, are contemplated and are within the scope of the presentinventions.

Moreover, there are many inventions described and illustrated herein.The present inventions are neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Moreover, each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, certainpermutations and combinations are not discussed and/or illustratedseparately herein. Notably, an embodiment or implementation describedherein as “exemplary” is not to be construed as preferred oradvantageous, for example, over other embodiments or implementations;rather, it is intended reflect or indicate the embodiment(s) is/are“example” embodiment(s).

FIG. 1A illustrates a block diagram representation of, for example, anexemplary integrated circuit including control circuitry, timing orclock circuitry, power supply circuitry and programmable/configurablelogic circuitry (which includes a plurality of logic tiles, each ofwhich may include transistors configured to perform combinational and/orsequential functions (simple and/or complex) and transistors (that maybe interconnected, for example, as multiplexers having two or moreinputs which are electrically interconnected into a network (see, forexample, the interconnect networks described and/or illustrated in U.S.Pat. No. 9,503,092 and U.S. Provisional Patent Application No.62/735,988; the '092 patent and '988 application are incorporated hereinby reference) as well as connected to, for example, associated datastorage elements, input pins and/or lookup tables that, when programmed,determine the operation and connectivity of the multiplexers));

FIG. 1B illustrates, among other things, a block diagram representationof a plurality of logic tiles (arranged in an array) of, for example, anexemplary FPGA, wherein input/output of the logic tiles may facilitatecommunication between the logic tiles and/or between certain logic tilesand circuitry external to the programmable/configurable logic circuitry;notably, the programmable/configurable logic circuitry may be comprisedof a plurality of programmable logic tiles wherein each logic tileincludes a plurality of multiplexers which are electricallyinterconnected into a network (e.g., a hierarchical network and/or meshnetwork); notably, the terms multiplexers and switches are used hereininterchangeably even though a switch may consist of a plurality ofmultiplexers;

FIG. 1C illustrates a block diagram representation of the interconnectarchitecture of one or more (or all) of the logic tiles of theprogrammable/configurable logic circuitry which include computingelements interconnected via a logic tile interconnect network (e.g., ahierarchical interconnect network or a mixed-mode interconnect network)wherein a plurality (or all) logic tiles are interconnected via atile-to-tile interconnect network (e.g., a mesh interconnect networkwherein a plurality of switches of a stage of the logic tileinterconnect network (e.g., the highest stage) are connected (viatile-to-tile interconnects) to a plurality of switches of a stage logictile interconnect network (e.g., the highest stage) of one or more otherlogic tiles; notably, the tile-to-tile interconnects and/or logic tileinterconnects may include uni-directional conductors and/or onebi-directional conductors;

FIG. 1D illustrates a block diagram representation of an M×N array ofswitch matrices, without detailed illustration of interconnection, of anexemplary logic tile of the programmable/configurable logic circuitry ofan FPGA; notably, any interconnect network now known or later developedmay be implemented in the logic tiles (e.g., hierarchical network and/ormesh network)—all of which may be employed in connection with thepresent inventions;

FIG. 2A illustrates a block diagram representation of a plurality oflogic tiles (e.g., arranged in an array of rows and columns—here, 2×2array of logic tiles—albeit the logic tile array (consisting of aplurality of logic tiles) may be any size (e.g., N×M)); in thisexemplary embodiment, each logic tile includes configuration data inputsto receive configuration data, configuration data outputs andconfiguration circuitry connected therebetween; here the configurationdata is written into the logic tile via the configuration data inputsfor use in the test sequences or the functional/normal mode; notably,the configuration outputs of a tile (e.g., Logic Tile 0,1 and Logic Tile1,1) may be connect to the configuration data inputs of another logictile (e.g., Logic Tile 0,0 and Logic Tile 1,0, respectively—adjacentlogic tiles in this illustrative embodiment) wherein the configurationdata may be written into each row or column of the plurality of thelogic tiles serially (in this illustrative embodiment, each row),therefore allow each tile to receive a unique set of configuration data(either for test mode, or functional/normal mode); as noted above, thelogic tiles may also include circuitry to facilitate read-back of theconfiguration test data after one or more logic tiles are programmed,configured or written with test data (prior to or after implementationof the test sequence); here, in response to a read-back operation, thetest mode configuration(s) and test data written to or loaded into suchlogic tile(s) may be read-back to, for example, verify the accuracy ofthe written data; in this embodiment, the read-back operation employsthe configuration port to read the configuration test data previouslywritten into the logic tile(s)—for example, via serial writing orloading of test mode configuration data to or into each row of theplurality of the logic tiles;

FIGS. 2B and 2C illustrate block diagram representations of a pluralityof logic tiles (e.g., arranged in an array of rows and columns—here, 2×2array of logic tiles—as noted above, the logic tile array (consisting ofa plurality of logic tiles) may be any size (e.g., N×M)), according tocertain aspects of the present inventions, wherein, in these embodiment,each logic tile includes configuration data inputs to receiveconfiguration test data and configuration circuitry connected thereto;here the configuration test data is written into each of the logic tilesvia the configuration data inputs, in parallel (i.e., at the same time),for use in the test sequences; that is, in this illustrative exemplaryembodiment, the logic tile array is configured in the parallel load testmode to receive the configuration test data at the configuration inputsof each logic tile in parallel wherein the test data is into the logictiles in parallel, and some or all tiles can be configured with the sameset of configuration test data; moreover, as illustrated in FIG. 2C, thetesting of the logic tiles may be implemented in parallel (e.g., thelogic circuitry and/or interconnect network of the logic tiles undergotesting in parallel); as noted above, it may be advantageous toelectrically isolate or disconnect selected circuitry of each of thelogic tiles from circuitry of other logic tiles of the array duringparallel testing of circuitry of the logic tiles (e.g., the interconnectnetwork or circuitry of the interconnect network of each logic tile maydisconnected from interconnect network(s) of other logic tiles therebypermitting one or more test sequences to be implemented on circuitry ofthe interconnect network of the logic tile at issue to determine oridentify whether of such circuitry is inoperative, faulty and/orinsufficiently reliable); in addition, as illustrated, the logic tilesmay include scan flip-flop circuitry to implement design for test (DFT)procedures/operation of certain commercially available IC testequipment/tools that employ DFT scan chains; notably, although notillustrated for reasons of focus on certain other inventive aspects, thelogic tiles of these embodiments may also include circuitry tofacilitate read-back of the configuration test data after one or morelogic tiles are programmed, configured or written with test data (priorto or after implementation of the test sequence);

FIG. 3A illustrates, in circuit block diagram form, an exemplaryschematic block diagram architecture for functional configuration of acore of a logic tile, during normal operation, according to certainaspects of the present inventions;

FIGS. 3B and 3C each illustrate selected portions, as identified in FIG.3A, of the exemplary schematic block diagram architecture for functionalconfiguration of a core of a logic tile of FIG. 3A;

FIG. 4A illustrates an exemplary timing diagram for the functionalconfiguration of a core of a logic tile (e.g., the exemplaryarchitecture of FIG. 3A); notably, the configuration data is writteninto a logic tile via the configuration data inputs (labeled here asBL_IN) for use during normal/functional operation; moreover, certain ofthe information identified on the exemplary timing diagrams (e.g.,number of cycles and amount of time) are merely exemplary and pertinentto certain particulars of the exemplary architecture of FIG. 3A (e.g.,bus width and layout as well as bitcell density and layout); suchinformation is not intended to be limiting, in any way, to the scope ofthe present inventions;

FIGS. 4B and 4C each illustrate selected portions, as identified in FIG.4A, of the exemplary timing diagram for the functional configuration ofa core of a logic tile of, for example, the exemplary architecture FIG.3A;

FIG. 5A illustrates, in circuit block diagram form, an exemplaryarchitecture for test mode configuration of a core of a logic tile,according to certain aspects of the present inventions;

FIGS. 5B and 5C each illustrate selected portions, as identified in FIG.5A, of the exemplary architecture for test mode configuration of a coreof a logic tile of FIG. 5A;

FIG. 6A illustrates an exemplary timing diagram for the test modeconfiguration of a core of a logic tile (e.g., the exemplaryarchitecture of FIG. 5A), according to certain aspects of the presentinventions; notably, the configuration test data is written into a logictile via the configuration data inputs (labeled here as BL_IN) for usein the test sequences; moreover, certain of the information identifiedon the exemplary timing diagrams (e.g., number of cycles and amount oftime) are merely exemplary and pertinent to certain particulars of theexemplary architecture of FIG. 5A (e.g., bus width and layout as well asbitcell density and layout); such information is not intended to belimiting, in any way, to the scope of the present inventions;

FIGS. 6B and 6C each illustrate selected portions, as identified in FIG.6A, of the exemplary timing diagram for the test mode configuration of acore of a logic tile of, for example, the exemplary architecture FIG.5A, according to certain aspects of the present inventions;

FIG. 7A illustrates, in circuit block diagram form, an exemplaryschematic block diagram architecture for configuration read-back of acore of a logic tile, according to certain aspects of the presentinventions, of the configuration data (programmed/stored in, forexample, the bitcells) and/or the test configuration data(programmed/stored in, for example, the bitcells during a test mode)after one or more logic tiles are programmed, configured or written withtest data (e.g., prior to or after implementation of the test sequence);notably, such read-back operation may be initiated or implemented by,for example, the test equipment/tool which may analyze the configurationdata and/or test configuration data that is read out of the logic tileor read back by such operation;

FIGS. 7B and 7C each illustrate selected portions, as identified in FIG.7A, of the exemplary schematic block diagram architecture forconfiguration read-back of a core of a logic tile of FIG. 7A;

FIG. 8 illustrates an exemplary timing diagram for a functionalconfiguration (i.e., for normal operation) of a core of a logic tile(e.g., the exemplary architecture of FIG. 3A) and a read-back operationof a core of a logic tile, according to certain aspects of the presentinventions; notably, the configuration data is written into bitcells ina logic tile via the configuration data inputs (labeled “BL_IN”) and,during a read-back operation, configuration data is read from the logictile via the configuration data outputs (labeled “BL_OUT”); certain ofthe information identified on the exemplary timing diagrams (e.g.,number of cycles and amount of time) are merely exemplary and pertinentto certain particulars of the exemplary architecture of FIG. 3A (e.g.,bus width and layout as well as bitcell density and layout); suchinformation is not intended to limiting, in any way, to the scope of thepresent inventions;

FIG. 9A illustrates an exemplary timing diagram of FIG. 8 for thefunctional configuration of a core of a logic tile (e.g., the exemplaryarchitecture of FIG. 3A); notably, the configuration data is writteninto a logic tile via the configuration data inputs (labeled as “BL_IN”)for use during normal/functional operation; as indicated above, certainof the information identified on the exemplary timing diagrams (e.g.,number of cycles and amount of time) are merely exemplary and pertinentto certain particulars of the exemplary architecture of FIG. 3A (e.g.,bus width and layout as well as bitcell density and layout); suchinformation is not intended to limiting, in any way, to the scope of thepresent inventions;

FIGS. 9B and 9C each illustrate selected portions, as identified in FIG.9A, of the exemplary timing diagram for the normal operationalfunctional configuration of a core of a logic tile of, for example, theexemplary architecture FIG. 3A, according to certain aspects of thepresent inventions;

FIG. 10A illustrates an exemplary timing diagram of FIG. 8 for theread-back operation of a core of a logic tile (e.g., the exemplaryarchitecture of FIG. 7A), according to certain aspects of the presentinventions; notably, the data read from the logic tile via theconfiguration data outputs (labeled “BL_OUT”) during a read-backoperation; again, certain of the information identified on the exemplarytiming diagrams (e.g., number of cycles and amount of time) are merelyexemplary and pertinent to certain particulars of the exemplaryarchitecture of FIG. 7A (e.g., bus width and layout as well as bitcelldensity and layout); such information is not intended to limiting, inany way, to the scope of the present inventions;

FIGS. 10B and 10C each illustrate selected portions, as identified inFIG. 10A, of the exemplary timing diagram, during a read-back operation,for the read-back configuration of a core of a logic tile (e.g., theexemplary architecture of FIG. 7A), according to certain aspects of thepresent inventions;

FIG. 11A illustrates, in circuit block diagram form, exemplary schematicblock diagrams of aspects of an architecture of an ReconfigurableBuilding Block (RBB) I/O logic, according to certain aspects of thepresent inventions; here, the schematic block diagram highlightsbitcell-configurable logic, scan-FF, and network I/Os; notably, “EFLX”is an acronym for the logic tile wherein “EFLX In” or “EFLX_In” refersto an input to or conductor connecting to the logic tile of a differentlogic tile or circuitry external to the logic tile array and “EFLX Out”or “EFLX_Out” refers to an output of or conductor connecting to adifferent logic tile or circuitry external to the array;

FIG. 11B illustrates, in block diagram form, exemplary I/O connectionsof a plurality of logic tiles (arranged in an exemplary 2×2 array oflogic tiles) illustrating (a) boundary or array perimeter I/Os of theinterconnect network and (b) inside or interior edge I/Os of theinterconnect network; “EFLX_In” refers to an input to a logic tile and“EFLX_Out” refers to an output of a logic tile; “EFLX_In” and “EFLX_Out”are conductors of logic tiles that are typically employed to connect tocircuitry external to the logic tile array; each of the arrows isrepresentative of a plurality of inputs and outputs disposed on theperimeter of the logic tiles; as noted above, the plurality of logictiles are arranged in an array of rows and columns—here, 2×2 array oflogic tiles—albeit the logic tile array (consisting of a plurality oflogic tiles) may be any size (e.g., N×M));

FIG. 11C illustrates, in circuit block diagram form, an exemplarysimplified block diagram of aspects of an architecture of interconnectnetwork connections at the boundary(ies) of a logic tile, according tocertain aspects of the present inventions, wherein the isolation controlsignal, when enabled, configures isolation circuitry to disconnect theinterconnect network from the interconnect network of the other logictiles of the array logic tiles; notably, “TILE_NWK_IN” “TILE_NWK_OUT”are acronyms for tile-to-tile interconnects from/to (respectively) aninterconnect network of another logic tile of the array of logic tiles(e.g., an adjacent logic tile); each of the arrows is representative ofa plurality of tile-to-tile interconnects disposed between theinterconnect networks of the logic tiles; that is, although fourtile-to-tile interconnects are illustrated herein, it is contemplatedthat there are many, many tile-to-tile interconnects to other logictiles of the array in order to facilitate certain types of tile-to-tilecommunications via the interconnect network each logic tile wherein forreasons of clarity only a few are illustrated herein;

FIG. 12A illustrates, in circuit block diagram form, exemplary schematicblock diagrams of aspects of an architecture of a ReconfigurableBuilding Block (RBB) logic, according to certain aspects of the presentinventions; here, the schematic block diagram highlightsbitcell-configurable logic, scan-FF, and network I/Os;

FIGS. 12B and 12C each illustrate selected portions, as identified inFIG. 12A, of the exemplary schematic block diagram architecture of theRBB logic (highlighting bitcell-configurable logic, scan-FF, and networkI/Os), according to certain aspects of the present inventions; and

FIGS. 13A and 13B sets forth exemplary code (suitable for implementationon the Mentor Graphics Tessent test tool/equipment) of the testprocesses/sequences or test modes for the RBB scan-FF scan chain and theconfiguration scan chain for a logic tile of the FPGA implementing oneor more of the architectures illustrates and described herein, accordingto certain aspects of the present inventions; notably, this code ismerely exemplary and not limiting in that other code to perform themethods and processes described herein; moreover, test tools/equipmentother than Mentor Graphics may be employed to perform one or more of theoperations/methods described and/or illustrated herein.

Again, there are many inventions described and illustrated herein. Anembodiment or implementation described herein as “exemplary” is not tobe construed as ideal, preferred or advantageous, relative to otherembodiments or implementations; rather, it is intended reflect orindicate the embodiment(s) is/are “example” or “illustrative”embodiment(s). Indeed, these inventions are neither limited to anysingle aspect nor embodiment thereof, nor to any combinations and/orpermutations of such aspects and/or embodiments. Each of the aspects ofthe present inventions, and/or embodiments thereof, may be employedseparately/alone or in combination with one or more of the other aspectsof the present inventions and/or embodiments thereof. For the sake ofbrevity, many of those combinations/permutations are not discussed orillustrated separately herein.

DETAILED DESCRIPTION

The present inventions are directed to circuitry and techniques to testa plurality of logic tiles of programmable/configurable logic circuitryof, for example, an FPGA (e.g., an embedded FPGA (e.g., embedded in aprocessor or ASIC)). In a first aspect, the test configuration data iscurrently (i.e., in parallel) loaded or written into a plurality oflogic tiles (e.g., all of the logic tiles of a logic tile array). Here,test configuration data is provided (e.g., currently) to a plurality oflogic tiles of the programmable/configurable logic circuitry andconcurrently written into one or more bitcells in a plurality of thelogic tiles. Thereafter, the circuitry in the logic tiles (e.g., all ofthe logic tiles of the programmable/configurable logic circuitry) may betested or undergo one or more test sequences to determine, assess and/orcharacterize the functionality and/or operability of the circuitry in/ofeach of the logic tiles.

In a second aspect, the present inventions are directed to circuitry andtechniques for testing, in parallel, a plurality of logic tiles (e.g.,all of the logic tiles of the programmable/configurable logiccircuitry). Here, one or more test sequences are performed on circuitryin each logic tile or each group of logic tiles concurrently in the testprocess/sequence of the programmable/configurable logic circuitry.Notably, the present inventions may implement any test sequence/processand/or test data/test mode configuration data now known or laterdeveloped; all of which are intended to fall within the scope of thepresent inventions.

In addition thereto, or in lieu thereof, in another aspect, the presentinventions are directed to circuitry and techniques to “isolate”circuitry of a logic tile during test (e.g., the interconnect networkand/or I/O circuitry). Here, the circuitry of a logic tile, which istypically connected to one or more logic tiles and/or circuitry externalto the array of logic tiles during normal operation, may be responsivelydisconnected from such one or more other logic tiles (e.g., the networkof one or more adjacent logic tiles). In one embodiment, tile-to-tileinterconnects and/or inputs/outputs of the logic tile may becommunicatively and/or electrically “disconnected” or “disabled” fromthe associated interconnects, circuitry and/or input/output of otherlogic tiles or external circuitry connected thereto. When, for example,the interconnect network of a logic tile under test is electrically“isolated” from interconnect network(s) of other logic tile(s) (to whichsuch interconnect network is connected to during normal or typicaloperation) during a test mode, the results or outcome of implementing atest sequence may be more readily determinative of whether interconnectnetwork and associated circuitry of the logic tile under test isfunctional, operative and/or reliable.

For example, the interconnect network and/or associated circuitry of alogic tile may be tested in isolation whereby such network/circuitry iseffectively disconnected from interconnect network(s) of other logictiles thereby permitting one or more test sequences to be implemented oncircuitry of the interconnect network of the logic tile at issue to morereadily determine or characterize, separate from other logic tile(s)(e.g., adjacent logic tile(s)), the integrity, operability and/orreliability of the circuitry of the logic tile(s) under test. In oneembodiment, isolation circuitry may be employed to disconnect or disableselected interconnects of one or more stages of the interconnect networkfrom stages of one or more associated interconnect network of otherlogic tile(s) (e.g., adjacent logic tile(s)) of theprogrammable/configurable logic circuitry. For example, output(s)interconnects of one or more stages of the interconnect network of thelogic tile under test or undergoing a test sequence that are connected,during normal operation, to an associated interconnect network(s) ofother logic tile(s) are looped back into the interconnect network duringperformance of a test sequence/process (e.g., a test sequence pertainingto the interconnect network). Any other I/Os that connects between twoor more (or all) logic tiles in functional or normal mode maybedisconnected and looped back in the same or a similar manner to theinterconnect network and RBB I/O Logic described herein. In this way,the impact of the operability or functionality of circuitry of otherlogic tile(s) (e.g., adjacent logic tile(s)) is limited and/oreliminated relative to the testing of circuitry of the logic tile undertest.

Test mode control circuitry (which, for example, is disposed in/on theintegrated circuit) may be employed to program or configure circuitry(e.g., multiplexers), input/output (I/O) and/or the switch interconnectnetwork of the logic tile(s) to program and/or configure one or more (orall) logic tiles in a test mode or test mode configuration prior toimplementation or performance of a test sequence/process. For example,the test mode control circuitry may issue one or more control signals tocircuitry of the logic tiles to, for example, implement or enable (i)writing or loading of test mode configuration data to or into aplurality (or all) of the logic tiles in parallel or sequentially,and/or (ii) testing of circuitry in a plurality (or all) of the logictiles in parallel or sequentially (e.g., using the test modeconfiguration data), and/or (iii) isolation circuitry in one or more (orall) of the logic tiles to disconnect circuitry under test fromcircuitry of other logic tile(s) (e.g., e.g., circuitry of adjacentlogic tile(s) that is connected during normal operation).

Moreover, the test mode control circuitry may also enable or facilitateread-back of the test data/configuration after one or more logic tilesare programmed, configured or written with test data (e.g., prior to orafter implementation of the test sequence). The read-back operation maybe employed to verify a test mode configuration(s) and/or test datawritten to or loaded into such logic tile(s). In addition thereto, or inlieu thereof, the read-back operation may access the data of testresults in order to assess the integrity, operability or functionalityof the circuitry under test (e.g., in each of the logic tiles). In oneembodiment, the read-back operation may employ the configuration port toread the test data/configuration previously written into the logictile(s)—for example, via parallel writing or loading of test modeconfiguration data to or into a plurality (or all) of the logic tiles ofthe programmable/configurable logic circuitry.

Notably, the integrated circuit may be, for example, a processor,controller, state machine, gate array, system-on-chip (SOC), and/orFPGA. Where the integrated circuit is a processor, controller, statemachine, gate array, system-on-chip (SOC), such IC may include anembedded FPGA having programmable/configurable logic circuitrycomprising a plurality of logic tiles (e.g., arranged in an array ofrow(s) and column(s)) wherein one or more (or all) of the logic tilesincludes programmable components.

In operation, to support configuration and/or reconfiguration of thecircuitry of the programmable/configurable logic circuitry (e.g., fullreconfiguration), each logic tile may store or use a relativelysignificant amount of data to configure, for example, the interconnectnetwork within the tile (e.g., Mbytes of configuration bits). In afunctional or operational mode (i.e., normal mode—as compared to testmode)), each logic tile of the programmable/configurable logic circuitry(used in or during normal operation) is configured prior to normaloperation. In one exemplary embodiment, the functional configurationport for each logic tile is 32 bits wide, thereby permitting each logictile of the array to be re-configured in approximately 50K cycles. Underthese circumstances, in an M×N array, the configuration time grows withN, for each column of tiles that is configured in series (See, e.g.,FIGS. 2A and 3A-3C). Notably, the configuration port may be a size/widthdifferent from 32-bit—e.g., 2/4/8/16/24/48/64 . . . -bit)—albeit 32-bitport or bus width is used herein for exemplary purposes).

In one embodiment, the configuration bits may be read-back afterconfiguration for verification and testing, and, in one embodiment, theread-back output may employ the configuration port (e.g., the 32 bitswide port mentioned above—albeit, in one embodiment, the read-backoutput may be a width different from the width of the configurationport). The read-back, verification, and testing operations/processes aredescribed in more detail below.

As mentioned above, in certain aspects, the present inventions includescircuitry and techniques to load or write test configuration datacurrently (i.e., in parallel) into a plurality of logic tiles (e.g., allof the logic tiles of a logic tile array). Here, test configuration datais provided (e.g., currently) to a plurality of logic tiles of theprogrammable/configurable logic circuitry and concurrently written intoone or more bitcells in a plurality of the logic tiles. The circuitryand techniques of these aspects of the present inventions maysignificantly reduce the test time and test channels (of the IC testequipment/tool) employed for loading or writing test configurationvectors into circuitry of the logic tiles (e.g., in certain embodiments,by greater than 100×). In one embodiment, the circuitry implemented inthe logic tiles, as well as techniques implemented by the logic tiles,facilitate a plurality or all of logic tiles in the logic tile arraybeing configured for test in parallel (e.g., logic tiles of the arrayare loaded or written with test configuration data concurrently). Inaddition thereto, or in lieu thereof, logic cores of a plurality or alllogic tiles of the array are configured, in one embodiment, using M(e.g., 4) bits of test configuration data—which conserves resources ofthe tester (e.g., channels of the tester). Where theprogrammable/configurable logic circuitry includes logic tiles havinglogic and/or one or more digital signal processor (DSP) cores, suchlogic tiles are configured, in one embodiment, using N+M (e.g., the 4bits of test configuration data plus 4 additional bits) of testconfiguration data—which again may conserve resources of the tester(e.g., channels of the IC test equipment/tool).

The present inventions are also directed to circuitry and techniques fortesting, in parallel, a plurality of logic tiles (e.g., all of the logictiles of the programmable/configurable logic circuitry). Here, one ormore test sequences are performed on circuitry in each logic tileconcurrently in the test process/sequence of theprogrammable/configurable logic circuitry. In one embodiment of theparallel test configuration, each core of a plurality of logic tilesundergoing test is also loaded or written with test configuration datain parallel. The test operation for each of such logic tiles, in thisaspect of the present inventions, is performed in parallel (i.e.,concurrently). For example, with reference to FIGS. 2B and 2C, the logictiles include a DFT configuration (note: “DFT” is an acronym for “designfor test” and refers to a test procedure or operation). Moreover, in oneexemplary embodiment, the core of each logic tile includes 8 balancedscan chains of 1300 (Logic Tile) to 2300 (DSP implemented Logic Tile)flip-flops each, connecting all its internal flip-flops (all scan-FFs).Notably, this configuration/implementation is recognizable by commercialDFT tools (e.g. Mentor Graphics Tessent IC test equipment/tool) as scanchains. Indeed, the DFT configuration chain is recognized by DFT toolsas a scan chain with shadow-registers (see configuration architecturedescribed/discussed below).

In addition thereto, or in lieu thereof, in one embodiment, the logictiles may be “isolated” wherein the circuitry of the logic tile (e.g.,I/O and/or interconnect network) is electrically disconnected fromexternal circuitry and/or associated circuitry of other logic tiles(e.g., the interconnect network of other logic tiles) and the testprocess/operation of the logic tiles may be performed in isolation(relative to other logic tiles of the array of logic tiles). Here, thecircuitry of a logic tile under test (e.g., the interconnect network) iselectrically “isolated” from circuitry connected thereto during normalor typical operation. In test mode, selected interconnects and/orinputs/outputs of the logic tile may be communicatively and/orelectrically “disconnected” or “disabled” from the associatedinterconnects, circuitry and/or input/output of other logic tiles orexternal circuitry connected thereto. For example, the output(s) ofinterconnects of one or more stages of the interconnect network of thelogic tile under test that connect to an associated interconnect networkof other logic tile(s) during normal operation are looped back into theinterconnect network of the logic tile during performance of a testsequence/process of the logic tile. Any other I/O (e.g., Logic I/Os inFIG. 11A) that connects between logic tiles in functional or normal modemaybe be disconnected and looped back in the same or a similar method tothe interconnect network (as described herein). In this way, the impactof the operability or functionality of circuitry of other logic tile(s)(e.g., adjacent logic tile(s)) is managed, limited and/or eliminatedrelative to the testing of circuitry of the logic tile under test.

Thus, in one embodiment, the test mode operation (e.g., scan process) ofeach logic tile of, for example, programmable/configurable logiccircuitry of an FPGA, includes:

-   -   1. Load or write the scan chain for configuration bits and        scan-FFs into the logic tiles to configure the array of logic        tiles;    -   2. Performance of test mode: capture data for x cycles (e.g., 1        to 8 cycles);    -   3. Unload or read-out the scan-FF output and check results;    -   4. Repeat steps 1-3 for each test vector until sufficient or        desired coverage is reached or attained.

The circuitry and techniques of the present inventions, in anotheraspect, are directed to test coverage for configurations of the logictiles (including, e.g., the interconnect networks within the core of thelogic tile). Here, the focus is on configuration bits and testing thecores (e.g., the logic circuitry and/or interconnect network (andcircuitry associated with the network)) of the logic tiles in relationto configuration bits. That is, once configured, a goal of testing thecore of one, some, a plurality or all of the logic tiles is to achievehigh coverage or confidence for all or substantially all configurations.Therefore, one of the present inventions is the circuitry and processesfor testing cores in relation to configuration bits and the logic andprocess controlled by these bits. In addition, it may be advantageous ifsuch cores of the logic tiles are “testable” using commercial DFT toolsand are “testable” within a commercially reasonably time using thecircuitry and techniques of the present inventions. With that in mind,in one aspect, the circuitry and techniques of the present inventionsprovide:

-   -   1. A configuration architecture that commercial DFT tools can        recognize;    -   2. High-coverage test patterns automatically through the        commercial DFT tool to configure the configuration bits of the        logic tile and control the scan-FFs thereof;    -   3. Fault-coverage data via the commercial DFT tool.

Notably, parallel-load, parallel-test mode techniques and circuitryprovide approximately 99% stuck-at coverage in a reasonable test time.Here, the test configuration data are loaded into the cores (e.g., thelogic circuitry and/or interconnect network (and circuitry associatedwith the network)) of the logic tiles in parallel. In addition thereto,or in lieu thereof, the cores of the logic tiles may be tested inparallel. Moreover, in one embodiment, the cores of the logic tiles aretested in isolation (relative to the cores of the other logic tiles)wherein the I/O pins that facilitate communication to other logic tilesof the array are “disabled” and electrically “disconnected” from theinterconnect network to isolate the logic tile relative to the otherlogic tiles of the array. (See, FIG. 2C). Here, in test mode, selectedinterconnects and/or inputs/outputs of the logic tile may becommunicatively and/or electrically “disconnected” or “disabled” fromthe associated interconnects, circuitry and/or input/output of otherlogic tiles or external circuitry connected thereto. Notably, “pins” arephysical points of entry/exit of the signal to the logic tile (e.g., theinterconnect network thereof); all physical forms of entry/exit of thesignal to the logic tile or circuitry of a logic tile are intended tofall within the scope of the present inventions.

In one exemplary embodiment/implementation, exemplary performancemetrics of a logic tile undergoing test performance are as follows:

Testable Faults 99.48% (parallel-load mode) Vector Count 500-1000(98-99% of all stuck-at faults) Tester Time ~5000 cycles per vector ~100μs per vector (@ 50 MHz) 50-100 ms for all vectors (@ 50 MHz) TesterChannels 12 channels (data) (1 × 1 array, logic) 10 channels (control)Tester Channels 8 + N * 8 channels (data) (m × N array, logic + DSP) 10channels (control)

In one embodiment, each logic tile may have a set or plurality of pinsthat are dedicated to the test mode or operation of the presentinventions. In addition, the logic tiles may share one or more pins withthe pins employed or used in or during normal operation of the logictiles. For example, such shared pins may be used during test mode aswell as configuration mode. Notably, a pin is a physical point ofentry/exit of the signal to the logic tile; all physical forms ofentry/exit of the signal to the logic tile are intended to fall withinthe scope of the present invention (for example, a conductor or metalrouting in/of an integrated circuit)

The “pins” and functionalities for an exemplary embodiment are listedbelow:

Pin Name Function Description Master DFT Mode Selection (Remainsconstant during the entire DFT operation) DFT_EN Enables Test Mode forthe core of 1: DFT operation the logic tile 0: Functional operationDFT_EN2 Enables DFT parallel test mode 1: DFT parallel test (isolationmode). mode 0: DFT full-array test mode BL_TEST_EN Enables DFT Test Modefor the 1: DFT configuration configuration scan chain 0: Functionalconfiguration BL_MUX2/4/8/16/32_S Enables 2/4/8/16/32-bit/cycle-core 1:2/4/8/16/32-bit/ for bitstream configuration cycle · core 0:1/2/4/8/16-bit/ cycle · core

Pin Name Function Description DFT Pins for RBB Scan Chain(Controlled/Captured by RBB Scan Test Procedure) DFT_SE Enables RBB scanchain selection for 1: load/unload scan-FF loading and unloading the RBBscan FF 0: Normal FF operation DFT_SI [7:0] RBB FF scan input forloading the RBB RBB FF scan data FF DFT_SO [7:0] RBB FF scan output forunloading the RBB FF scan output RBB FF DFT_CLK_SEL_IN RBB clockselection for DFT mode 1: Select DFT_CLK_IN 0: Selection functionalclock(s) DFT_CLK_IN When DFT_CLK_SEL_IN is 1, all FFs in DFT clock forscan and the core are clocked by DFT_CLK_IN low-speed capture insteadfunctional clock(s). This is used to load/unload scan-FF and to performlow-speed capture

Pin Name Function Description DFT Pins for Configuration Scan Chain(Controlled by Configuration Scan Test Procedure) INIT Enables bitstreamconfiguration mode 1: Bitstream for scanning in the configuration bitsConfiguration during DFT 0: Normal Operation SE_CLK0 Non-overlappingconfiguration clock

 Leading edge SE_CLK1 Non-overlapping configuration clock

 Trailing edge BL_SE Bit-line scan enable 1: Advances the BL scan chainby 1 FF/ cycle 0: BL scan disabled BL_TEST_IN [31:0] Bit-line scan inputfor DFT bitstream DFT Configuration configuration data BL_TEST_OUT[31:0]Bit-line scan output for DFT bitstream DFT Configuration configurationof the next core above, data holds the same data as BL_TEST_IN[31:0]WL_SE Word-line scan enable 1: Advances the WL scan chain by 1 FF/ cycle0: WL scan disabled WL_IN Word-line scan input. 1: Selects the WLPropagates a “1” down the WL scan column to write chain to select the WLcolumn to write WL_EN Word-line write assertion. 1: Writes data from BLIn write mode, this writes the BL scan- scan (when RD_EN = chain datainto the bitcells in the WL 0) column selected by the WL scan-chain orIn read-back mode, this read the Read data from bitcell-data in the WLcolumn selected bitcell (when by the WL scan-chain onto the BL RD_EN= 1) scan-chain RD_EN Control signal for configuration read- 1: Bit-cellread mode back from bitcells onto BL scan chain 0: Bit-cell write modeto be shifted out BL_IN [31:0] Bit-line scan input for functionalFunction configuration bitstream configuration (NOT used data during DFTmode) BL_OUT[31 :0] Bit-line scan output from the current Functionconfiguration core to the next core above. In data functional mode, thisis the or configuration data to program the next Configuration read-core. back data In read-back mode, this is the configuration read-backof the bitcell in the current core.

With reference to FIGS. 3A-3C and 4A-4C, in one exemplary embodiment,functional configuration data is input into the logic tile via bit lines(e.g., BL_IN[31:0]), which (in addition) propagates vertically to thenext/adjacent tile above (where the data propagation is from bottom totop), and word-line (WL) controls the column of bitcells (BC) to writeto, which propagates horizontally to the next/adjacent tile (e.g., theadjacent tile to the right where the data propagation is from left toright). In this exemplary embodiment, there are 2048 columns of BC banks(WL_SZ=2048), and 704 rows (BL_SZ=704). (See, FIGS. 3A-3C). Since BLdata is scanned in this exemplary embodiment up to 32-bit parallel, eachBL chain segment may be 22-bits deep (704/32), and 2048 banks arewritten for the full configuration. Notably, in one embodiment, theconfiguration circuitry does not employ address-decoders to write to thebitcells. In this way, the area of the configuration circuitry isreduced.

With continued reference to FIG. 4A-4C, in this exemplary embodiment,the bitcells may be written by scanning in one column of BL data throughthe BL scan chain (e.g., driven by non-overlapping clocks SE_CLK0 andSE_CLK1) for BL_SZ/32 cycles to populate the entire BL scan chain; theWL scan chain is then advanced by one column (e.g. from WL[0] to WL[1]),and then asserting WL_EN to write to the selected column. In thisexemplary embodiment, it takes a total of WL_SZ write operations topopulate the entire array of configuration bits.

In one exemplary embodiment, the configuration operation or process ofthe logic tile may use approximately 50K cycles to configure each corein 32-bit write mode (albeit the width of the port may be greater thanor less than 32 bits—e.g., 2/4/8/16/24/48/64 . . . -bit). Notably, thetime to configure the logic tiles increases as N·50K cycles for an M×Narray. While this may be acceptable for functional mode because the coreis configured typically once during power-up and usually notre-configured until the next power-up sequence. However, in testoperation or mode, this may result in too long a test time because500-1000 vectors is generally required to reach suitable confidence orcoverage, which means up to N·50 million tester cycles and 32 testerchannels just for configuration data.

In certain embodiments/implementations of the present inventions, thetest mode configuration time has been reduced to 2.5-5 million testercycles, and only 4 tester channels for the logic tile, and both testerchannels and tester cycles are largely independent of any M×N arraylayout.

The DFT test mode configuration process or procedure is similar to thenormal bitstream configuration process, except, in one exemplaryembodiment:

-   -   1. BL_TEST_IN[31:0] pin instead of BL_IN[31:0] are used to scan        in the configuration data    -   2. BL_TEST_IN[31:0] is directly sent to BL_TEST_OUT[31:0] to        drive the BL_TEST_IN of next core above    -   3. Only 4 unique bits (BL_TEST_IN[3:0]) is required to drive the        32-bit BL_TEST_IN port to save tester channels, and the BL scan        time is still only 22 cycles (704/32) per bank    -   4. Only 224 WL column writes are required in DFT mode (as        opposed to 2048 WL columns in functional mode) to write all 2048        banks of bit cells (BCs).

With reference to FIGS. 5A-5C and 6A-6C, in one exemplary embodiment,the test mode configuration technique initially executes theconfigurations scan chain to configure the core of the logic tile. It issimilar to the normal bitstream configuration process, except BL_TEST_INpins are used to scan in the configuration data. As shown below, in oneexemplary embodiment, data is written into the bitcells by scanning inone column of BL data through the BL scan chain (driven bynon-overlapping clocks SE_CLK0 and SE_CLK1) for BL_SZ/32 cycles topopulate the entire BL scan chain; the WL scan chain is then advanced byone column (e.g. from WL[0] to WL[1]), and then asserting WL_EN to writeto the selected column. Under these circumstances, the testconfiguration uses a total of 224 write operations to populate thebitcells of the entire array of logic tiles with configuration bits fortest mode, regardless of the size of the array of logic tiles. Notably,other port dimensions and timing techniques are intended to fall withinthe scope of the present inventions.

After configuration of the logic tiles is complete for test mode, inthis exemplary embodiment, RBB scan chain may be loaded via the DFT_SI[7:0] pin to initialize all the RBB FFs to the desired state. This scanis similar to the scan chain in ASICs: the DFT_SE pin puts all the RBBscan-FFs in scan mode, and the scan data is shifted in serially. Thecore of the logic tile then operates for N cycles (determined by thetest-vector, generally 1-8 cycles), and the states of the RBB FFs arescanned out via DFT_SO to be analyzed for any mismatches.

In those exemplary embodiments where there is non-overlapping clocks onSE_CLK0 and SE_CLK1 (see FIGS. 6A-6C), the timeplate for configurationmay employ four steps, so the 5K cycles for configuration would be thebottle neck for test time except for larger (greater than 4×4) arrays.Because the Scan-FF data is concatenated M times for an M×N array (FIG.1.2), loading/unloading of the 1500-2500 scan-FF's per scan chain percore can become the bottle neck for test time in large arrays. But sincethe scan-FF can operate on a 2-step template, a 2× reduction in scan-FFtester cycles can be achieved (by packing 2 data samples into a 4-steptimeplate) if scan-FF load/unload becomes the bottleneck for test time.

As noted above, in one aspect of the present inventions, configurationarchitecture of the logic tile implements, provides and/or supportsconfiguration read-back operations. With reference to FIGS. 7A-7C, 8,9A-9C and 10A-10C, in one exemplary embodiment, configuration data maybe read-back from the bitcells via output port BL_OUT (in this exemplaryembodiment a 32 bit output port labeled BL_OUT[31:0]). The BL buffers incan be configured as sense-amplifiers (SA buf or buffer, see—FIG. 4C)during read-back (e.g., RD_EN=1), where the selected bank would have itsBL tri-stated by the sense-amplifier, so the BC can drive the BL totheir stored data, and the remaining sense-amps would buffer the BL datato drive to the right side, where it is multiplexed or muxed into the BLscan chain.

A primary element of the logic blocks is Look-Up-Tables (LUTs), whichreside in Reconfigure Building Blocks (RBB) along with flip-flops andauxiliary logic such as data mux and carry chain. In one exemplaryembodiment, each logic tile-memory core contains 2,520 6-input LUTs from630 RBBs. Moreover, each core of the logic tile contains 316 I/O blocks,each providing 2 inputs and 2 outputs for a total of 632 inputs and 632outputs per core. The I/O RBB microarchitecture diagram is illustratedin FIG. 11A.

With reference to FIG. 11A, the I/O RBB receives input data into thecore (e.g., the logic circuitry of the logic tile) of the logic tilefrom, for example, circuitry external to the array of logic tiles (suchas an SoC), which goes through the optional FF before sending to theinterconnect network of the logic tile via pins 10 and 11. The I/O RBBmay also be employed to receive input from the interconnect via pins 00and 01, which in this exemplary embodiment goes through the optional FFbefore sending to the output (EFLX_OUT[0] and EFLX_OUT[1]) of the logictile, which drives the external circuitry (e.g., SoC).

During the processes of the test mode (DFT_EN=1), asynchronous resetlogic driven by the interconnect network input SR may be disabled toavoid asynchronous reset from being asserted during scan. To not losecoverage, asynchronous reset through dedicated reset pin, CHIP_RSTremains supported. Notably, the test mode, in one embodiment, alsoenables the clock-gating cell, regardless of the clock-enable signal CEfrom the interconnect network.

These test mode gated signals (such as CE and SR) may be captured byauxiliary logic into the DFFs (note: “DFF”=D flip/flop) to maintainobservability. The DFFs in the logic tile RBBs may be scan-FFs.

With continued reference to FIG. 11A, DFT_EN2 is an input signal whichcontrols the parallel test mode of the test mode processes. To betterunderstand its purpose/function, it is helpful to first understand howthe logic tile I/Os are connected in an array in one embodiment (seeFIG. 11B). Here, when a plurality of logic tiles are arrayed together,the logic tile I/Os on the interior of the perimeter of the array (i.e.,not on the outer perimeter of the array) are generally not utilized, andmay be connected with the neighboring I/Os. In this way, the logic tileoutput drives a logic tile input of the neighboring logic tile, and viceversa (see FIG. 11B). Interconnect network I/Os are connected in thesame manner, except the boundary interconnect inputs may be terminatedor tied-off.

Under these circumstances and in this implementation, each core (e.g.,logic circuitry) of the logic tile cannot be tested in isolationrelative to the interconnect networks of neighboring logic tiles (i.e.,physically adjacent thereto), because its EFLX_IN values depends on theoutputs from its neighboring tiles, as well as inputs from the SoC. Thismay make logic tile testing problematic, since its input from the SoC isdriven to known states, and a fault in one logic tile may cause anotherlogic tile to observe a defect, which is not desirable forfault-isolation and fault-detection.

Therefore, most (e.g., 98-99%) of stuck-at faults may be detected inparallel-load mode, which has DFT_EN2 asserted to 1. This gates offEFLX_IN from entering the core of the logic tile, and instead loops-backEFLX_OUT into the EFLX_IN ports (see FIG. 11A). In this way, testing ofthe logic tiles may be performed isolated and disconnected from theinputs/outputs of the interconnect network of neighboring tiles or, forexample, external circuitry (such as am SoC) during performance of thetest mode. In addition, in one embodiment, the logic tiles or DSP coresin the array of logic tiles may be loaded with the same configurationdata and the same scan-FF data and the test process for each logic tilemay be tested in parallel. In this way, the test mode time may besignificantly reduced; and, in addition, the tester channels are alsoreduced.

The interconnect network I/Os of the logic tiles (i.e., the tile-to-tileinterconnects) may be configured or connected in the same manner (see,for example, FIG. 11C). At the interconnect network portion of the coreboundary, TILE_NWK_IN and TILE_NWK_OUT ports connect to the TILE_NWK_OUTand TILE_NWK_IN ports of the interconnect network of neighboring logictiles, respectively. When DFT_EN2 is asserted, parallel-load model maybe enabled and TILE_NWK_OUT is looped-back into TILE_NWK_IN to test theinterconnect network or fabric of each logic tile in isolation ordisconnected from the interconnect network of each of the other logictiles of the logic tile array, like that with the I/Os EFLX_IN andEFLX_OUT (see FIG. 11A). In this way, the logic tile may be furtherisolated by disconnecting the interconnect network from adjacent orneighboring logic tiles during performance of the test mode.

Thus, in test mode, each logic tile may be isolated from connections tothe input/output and/or the interconnect network of other logic tiles ofthe logic tile array. These features may be implemented in any of theembodiments described and/or illustrated herein.

Notably, “EFLX_IN” and “EFLX_OUT” in FIG. 11B are representative of theplurality of inputs and outputs of the logic tiles. Similarly,TILE_NWK_IN and TILE_NWK_OUT are representative of a plurality oftile-to-tile interconnects between interconnect networks of neighboringlogic tiles. For example, in one exemplary embodiment, each logic tilehas 4096 TILE_NWK_IN and TILE_NWK_OUT signals per side, as well as 632EFLX_IN and EFLX_OUT signals per core. Having these inputs and outputselectrically disconnected, gated or turned off and outputs looped backinevitability results in some loss of certain coverage. However, it maybe advantageous to implement the test mode process and circuitry tomaintain the coverage loss to a minimum. In one embodiment,parallel-load results in a <0.5% loss in stuck-at test coverage, but issufficient for 98-99% stuck-at fault coverage.

In those instances where higher test coverage is desired (e.g. 99.8%),an additional full-array testing mode may be implemented as asupplement, which disables DFT_EN2 and test the entire array as a largefabric, including all the core-to-core connections. Such animplementation may result in a larger test time relative to otherimplementations described above.

Other than I/O RBBs and interconnect, most of the reconfigurable logicis in the Logic RBB. An exemplary micro-architecture block diagramschematic is illustrated in FIGS. 12A-12C. In one embodiment, each LogicRBB contains 4 pairs of 5-input LUTs, which can behave as single 6-inputLUTs. With reference to FIG. 12A-12C, the bit-cell configurable logiccells (shown in grey) are controlled by configuration bits in thisexemplary embodiment. These fall in 2 major categories, LUT and FF:

-   -   1. LUT behave very much like ROMs, where the ROM values are        programmed by the configuration bits, and the LUT input behaves        like the ROM address (e.g. A1:A6), which reads out the value        from the ROM onto its output (OA0 and OA1 in 5-input LUT mode,        or A in 6-input LUT mode).        -   Based on the mode configured, the LUT output can directly            drive the interconnect network (via outputs A, B, C, and D),            or be sent into additional multiplexers or muxes (e.g. A7,            C7, X8) to form wider LUTs, or be sent to a carry chain to            perform addition, subtraction, comparator (e.g. Cout, Sout),            which is sent to the interconnect network (via outputs AMUX,            BMUX, CMUX, and DMUX). The data input selection for            multiplexers AMUX, BMUX, CMUX, and DMUX are also controlled            by bitcells based on the configuration.    -   2. FFs in RBBs are standard scan-DFFs. Each RBB has 4 primary        FFs, AQ, BQ, CQ, and DQ, which can select from a number of input        signals, including LUT output, mux output, carry chain output,        or flop directly the interconnect network inputs AI, BI, CI,        and DI. These FF outputs AQ, BQ, CQ, and DQ are directly sent to        the interconnect network. There are other applications where the        4 secondary FFs are required, such as:        -   a. Dual-5-input LUTs where both output (e.g. OA0 and OA1            needs to be flip-flopped (FF'ed))        -   b. Delay lines or synchronization FF's where back-to-back            FF's are required (e.g. AQ FF sending data directly into OAQ            FF).        -   c. High-density logic packing where (for example) LUT A is            driving signal to AQ FF, while interconnect input AI is            driving signal into OAQ FF.    -   These example cases require both primary and secondary FF's to        be used, and the secondary FF's OAQ, OBQ, OCQ, and ODQ would        connect to the interconnect network via multiplexers AMUX, BMUX,        CMUX, and DMUX.    -   Synchronous set-reset of each FF is controlled by configuration        bits, where the D inputs to the FF could be asserted high or low        when SR signal is asserted.    -   Asynchronous set/reset for primary FF and secondary FF are        driven by separate QCLR and OQCLR signals, respectively, which        are controlled by configuration bits. During DFT mode, SR cannot        control QCLR and OQCLR signals, only CHIP_RST can.

During test mode (DFT_EN=1), asynchronous reset logic driven by theinterconnect network input SR may be disabled to avoid asynchronousreset from being asserted during scan. To avoid loss of coverage,asynchronous reset through dedicated reset pin, CHIP_RST remainssupported. DFT mode also enables the clock-gating cell, regardless ofthe clock-enable signal CE from the interconnect network.

Notably, it may be advantageous that DFT-gated signals such as CE and SRare captured by auxiliary logic into the DFFs in order to maintainobservability.

During each load procedure of scan chain, the configuration bits and thedata for the RBB scan-FFs must both be loaded. For the unload procedure,only the RBB scan-FFs may be scanned out to verify the function of thecore of the logic tile. As discussed above, the configuration bitsread-back may be performed separately, and, in one embodiment, notre-verified for each vector in order to eliminate or save tester time.

Using the test circuitry architecture and processes discussed abovefacilitates implementation of the test process on commercial DFT tools(e.g. Mentor Graphics Tessent) which permits creation and use oftest-vectors to control both the configuration bits and the scan-FFs.

For example, employing 500-1000 different configurations facilitatesachieving 98-99% stuck-at coverage at the core level. Less than 0.5% ofcoverage loss is due to input-gating and output-loopback at thetile-to-tile boundary of the logic tile. This coverage loss in returnfor significantly shorter tester time and tester channels may beconsidered a worthwhile tradeoff. Where additional coverage is desired(e.g. 99.8% or higher), a full-array test mode may be employed (whereDFT_EN2=0) to reach the additional 0.5% coverage at the expense ofadditional vectors.

As mentioned above, most of the LUTs in logic tile function or behavelike ROMs, where the ROM values are controlled by configuration bits.However, a small portion of the LUTs can have their ROM values bemodifiable at run-time, making them behave like RAMs in certainconfigurations. Based on configuration, these LUTs may behave or performlike LUT, single-port RAM, dual-port RAM, or shift-registers. In oneembodiment, a logic tile has 20 Kb of “RAM” per core, while the DSP corehas 1 Kb of “RAM” per core.

Notably, exemplary code (for Mentor Graphics Tessent) of the testprocesses or modes for the RBB scan-FF scan chain and the configurationscan chain for a logic tile are set forth in FIGS. 13A and 13B. Thiscode is merely exemplary and other code may be suitable. It should beappreciated that methods set forth in FIGS. 13A and 13B may include anynumber of additional or alternative operations and/or functions;moreover, certain operations/functions shown in FIGS. 13A and 13B neednot be performed in the illustrated order, and the methods illustratedin FIGS. 13A and 13B may be incorporated into a more comprehensiveprocedure or process having additional functionality not described indetail herein.

As noted above, there are many inventions described and illustratedherein. For example, the present inventions are directed to circuitryand techniques for testing, in parallel, a plurality of logic tiles ofan integrated circuit. In addition thereto, or in lieu thereof, thepresent inventions are directed to circuitry and techniques for writingor loading, in parallel, configuration data (e.g., test modeconfiguration data) into a plurality of logic tiles (e.g., bit cells) todetermine or assess the functionality and/or operability of thecircuitry in/of each of the logic tiles. In one embodiment, circuitry ofeach of a plurality of or all logic tiles are tested or undergo one ormore test sequences concurrently (i.e., at the same time) in a testprocess/sequence of the programmable/configurable logic circuitry. Inanother embodiment, circuitry of each of the plurality of logic tilesare tested serially wherein one or more of the test sequence(s) areperformed with respect to circuitry of each logic tile or each group oflogic tiles at different times (e.g., sequentially from the other logictiles and/or groups of logic tiles of the programmable/configurablelogic circuitry). Notably, the present inventions may implement any testsequence/process and/or test data/test mode configuration data now knownor later developed; all of which are intended to fall within the scopeof the present inventions.

The present inventions are also directed to isolating or disconnectingcircuitry of the logic tiles from circuitry of other logic tiles. In oneembodiment, circuitry of the logic tiles is electrically disconnectedfrom circuitry of other logic tiles (e.g., neighboring logic tiles)and/or circuitry external to the programmable/configurable logiccircuitry during performance of a test sequence/process. Thus, a logictile may be configured such that the interconnect network of that logictile may be effectively disconnected from one or more (or all)interconnect network(s) of other logic tiles of the array. For example,where the logic tile is undergoing test, the circuitry of a logic tilemay be configured to be electrically isolated from circuitry of otherlogic tile(s) which is/are connected thereto during normal or typicaloperation.

For example, in test a mode, the interconnect network (or circuitryassociated with the interconnect network) of a logic tile may beelectrically “disconnected” from the associated interconnects andcircuitry of other logic tiles to assess the functionality of theinterconnect network and/or circuitry associated with the interconnectnetwork in isolation. In one embodiment, isolation circuitry may beenabled to disconnect or disable selected interconnects of one or morestages of the interconnect network from stages of one or more associatedinterconnect network of other logic tile(s) (e.g., adjacent logictile(s)) of the programmable/configurable logic circuitry. For example,the output(s) of interconnects of one or more stages of the interconnectnetwork of the logic tile under test or undergoing a test sequence thatconnect to an associated interconnect network of other logic tile(s)during normal operation are looped back into the interconnect network ofsuch logic tile during performance of a test sequence/process of thelogic tile (e.g., a test sequence pertaining to the interconnectnetwork). Any other I/O (e.g., the I/Os in FIG. 11A) that connectsbetween logic tiles in functional or normal mode maybe be disconnectedand looped back in the same or a similar method to the interconnectnetwork and/or the RBB I/O logic (as described herein). In this way, theimpact of the operability or functionality of circuitry of other logictile(s) (e.g., adjacent logic tile(s)) is managed, limited and/oreliminated relative to the testing of circuitry of the logic tile undertest.

Notably, the isolation circuitry may be employed in the test mode and ina non-test mode (i.e., during normal operation of theprogrammable/configurable logic circuitry and/or FPGA) in order todisconnect certain circuitry (for example the interconnect network) fromcircuitry of other logic tiles to which is, under typically operatingconditions, capable of being connected (i.e., it is capable of beingconnected when the logic tiles are programmed with normal/functionalconfiguration data for a normal/functional configuration).

In one embodiment, control circuitry (which, for example, is disposedin/on the integrated circuit) program or configure circuitry of thelogic tile(s) (I/O and/or circuitry associated with the switchinterconnect network to program) in a test mode or test modeconfiguration. The control circuitry may also issue test modecommands—for example, one or more control signals to circuitry of thelogic tiles to, for example, implement or enable (i) writing or loadingof test mode configuration data to or into a plurality (or all) of thelogic tiles in parallel or sequentially, and/or (ii) testing ofcircuitry in a plurality (or all) of the logic tiles in parallel orsequentially (e.g., using the test mode configuration data), and/or(iii) isolation circuitry (e.g., multiplexers) in one or more (or all)of the logic tiles to disconnect the logic tile from circuitry orconductors other logic tiles (e.g., circuitry of neighboring logictile(s) that is connected during normal operation) and/or circuitryexternal to the logic tile array.

The control circuitry, in one embodiment, may also enable read-backoperations. A read-back operation may be employed to verify a test modeconfiguration(s) and/or test data written to or loaded into such logictile(s). In addition thereto, or in lieu thereof, the read-backoperation may access the data of test results in order to assess theintegrity, operability or functionality of the circuitry under test(e.g., in each of the logic tiles). In one embodiment, the read-backoperation may employ the configuration port to read out data from thelogic tiles (e.g., test mode configuration data previously written intocircuitry (e.g., bitcells) in response to a test sequence. The controlcircuitry may program or configure one or more (or all) logic tilesduring a test sequence—for example, when the integrated circuit isconnected to IC test equipment.

Again, there are many inventions described and illustrated herein. Whilecertain embodiments, features, attributes and advantages of theinventions have been described and illustrated, it should be understoodthat many others, as well as different and/or similar embodiments,features, attributes and advantages of the present inventions, areapparent from the description and illustrations. As such, theembodiments, features, attributes and advantages of the inventionsdescribed and illustrated herein are not exhaustive and it should beunderstood that such other, similar, as well as different, embodiments,features, attributes and advantages of the present inventions are withinthe scope of the present inventions.

Indeed, the present inventions are neither limited to any single aspectnor embodiment thereof, nor to any combinations and/or permutations ofsuch aspects and/or embodiments. Moreover, each of the aspects of thepresent inventions, and/or embodiments thereof, may be employed alone orin combination with one or more of the other aspects of the presentinventions and/or embodiments thereof.

Notably, reference herein to “one embodiment” or “an embodiment” (or thelike) means that a particular feature, structure, or characteristicdescribed in connection with the embodiment may be included, employedand/or incorporated in one, some or all of the embodiments of thepresent inventions. The usages or appearances of the phrase “in oneembodiment” or “in another embodiment” (or the like) in thespecification are not referring to the same embodiment, nor are separateor alternative embodiments necessarily mutually exclusive of one or moreother embodiments, nor limited to a single exclusive embodiment. Thesame applies to the term “implementation.” The present inventions areneither limited to any single aspect nor embodiment thereof, nor to anycombinations and/or permutations of such aspects and/or embodiments.Moreover, each of the aspects of the present inventions, and/orembodiments thereof, may be employed alone or in combination with one ormore of the other aspects of the present inventions and/or embodimentsthereof. For the sake of brevity, certain permutations and combinationsare not discussed and/or illustrated separately herein.

Further, an embodiment or implementation described herein as “exemplary”is not to be construed as ideal, preferred or advantageous, for example,over other embodiments or implementations; rather, it is intended conveyor indicate the embodiment or embodiments are example embodiment(s).

Although the present inventions have been described in certain specificaspects, many additional modifications and variations would be apparentto those skilled in the art. It is therefore to be understood that thepresent inventions may be practiced otherwise than specificallydescribed without departing from the scope and spirit of the presentinventions. Thus, embodiments of the present inventions should beconsidered in all respects as illustrative/exemplary and notrestrictive.

Notably, various circuits, circuitry and techniques disclosed herein maybe described using computer aided design tools and expressed (orrepresented), as data and/or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, and/or othercharacteristics. Formats of files and other objects in which suchcircuit, circuitry, layout and routing expressions may be implementedinclude, but are not limited to, formats supporting behavioral languagessuch as C, Verilog, and HLDL, formats supporting register leveldescription languages like RTL, and formats supporting geometrydescription languages such as GDSII, GDSIII, GDSIV, CIF, MEBES and anyother formats and/or languages now known or later developed.Computer-readable media in which such formatted data and/or instructionsmay be embodied include, but are not limited to, non-volatile storagemedia in various forms (e.g., optical, magnetic or semiconductor storagemedia) and carrier waves that may be used to transfer such formatteddata and/or instructions through wireless, optical, or wired signalingmedia or any combination thereof. Examples of transfers of suchformatted data and/or instructions by carrier waves include, but are notlimited to, transfers (uploads, downloads, e-mail, etc.) over theInternet and/or other computer networks via one or more data transferprotocols (e.g., HTTP, FTP, SMTP, etc.).

Indeed, when received within a computer system via one or morecomputer-readable media, such data and/or instruction-based expressionsof the above described circuits may be processed by a processing entity(e.g., one or more processors) within the computer system in conjunctionwith execution of one or more other computer programs including, withoutlimitation, net-list generation programs, place and route programs andthe like, to generate a representation or image of a physicalmanifestation of such circuits. Such representation or image maythereafter be used in device fabrication, for example, by enablinggeneration of one or more masks that are used to form various componentsof the circuits in a device fabrication process.

Moreover, the various circuits, circuitry and techniques disclosedherein may be represented via simulations using computer aided designand/or testing tools. The simulation of the circuits, circuitry, layoutand routing, and/or techniques implemented thereby, may be implementedby a computer system wherein characteristics and operations of suchcircuits, circuitry, layout and techniques implemented thereby, areimitated, replicated and/or predicted via a computer system. The presentinventions are also directed to such simulations of the inventivecircuits, circuitry and/or techniques implemented thereby, and, as such,are intended to fall within the scope of the present inventions. Thecomputer-readable media corresponding to such simulations and/or testingtools are also intended to fall within the scope of the presentinventions.

The terms “comprises,” “comprising,” “includes,” “including,” “have,”and “having” or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, circuit, article,integrated circuit or apparatus that includes/comprises a list ofelements, components, steps (etc.) does not include only those elements,components, steps (etc.) but may include other elements, components,steps (etc.) not expressly listed or inherent to such process, method,circuit, article, integrated circuit or apparatus. Further, use of theterms “connect”, “connected”, “connecting” or “connection” throughoutthis document should be broadly interpreted to include direct orindirect (e.g., via one or more conductors and/or intermediatedevices/elements (active or passive) and/or via inductive or capacitivecoupling)) unless intended otherwise (e.g., use of the terms “directlyconnect” or “directly connected”).

The terms “a” and “an” herein do not denote a limitation of quantity,but rather denote the presence of at least one of the referenced item.Further, the term “logic tile” means a design unit or block of aplurality of transistors (typically more than thousands), which, in thisapplication, is capable of connecting to a plurality of neighboring“tiles”, “cores” or “blocks”. The term (i) “integrated circuit” means,among other things, a processor, controller, state machine, gate array,SoC, PGA and/or FPGA. The term (i) “integrated circuit” also means, forexample, a processor, controller, state machine and SoC—including anembedded FPGA. For the avoidance of doubt, field programmable gate arrayor FPGA means both an FPGA and an embedded FPGA.

In addition, the term “circuitry”, means, among other things, a circuit(whether integrated or otherwise), a group of such circuits, one or moreprocessors, one or more state machines, one or more processorsimplementing software, one or more gate arrays, programmable gate arraysand/or field programmable gate arrays, or a combination of one or morecircuits (whether integrated or otherwise), one or more state machines,one or more processors, one or more processors implementing software,one or more gate arrays, programmable gate arrays and/or fieldprogrammable gate arrays. The term “data” means, among other things, acurrent or voltage signal(s) (plural or singular) whether in an analogor a digital form, which may be a single bit (or the like) or multiplebits (or the like). The term “multiplexers” means multiplexers and/orswitches.

Further, the term “initialization operation” means the power-up,start-up, initialization, re-initialization, configuration, and/orre-configuration operation of the logic tile, logic tile array and/orthe integrated circuit including the logic tile array. The term dataprocessing operations means operations including digital signalprocessing, encoding, decoding, encrypting, decrypting and/or otherforms of data manipulation. Moreover, the terms “first,” “second,” andthe like, herein do not denote any order, quantity, or importance, butrather are used to distinguish one element from another.

What is claimed is:
 1. An integrated circuit comprising: a fieldprogrammable gate array including: a plurality of logic tiles, wherein,during operation of the field programmable gate array, each logic tileis configurable to connect with at least one other logic tile of theplurality of logic tiles, and wherein each logic tile of the pluralityof logic tiles includes: a normal operating mode, a test mode, aninterconnect network including a plurality of multiplexers, whereinduring operation of the field programmable gate array, the interconnectnetwork of each logic tile is configurable to electrically connect withthe interconnect network of at least one other adjacent logic tile ofthe plurality of logic tiles via one or more tile-to-tile interconnectsin the normal operating mode, and bitcells to store data; and controlcircuitry, electrically connected to each logic tile of the plurality oflogic tiles, to enable concurrently writing configuration test data intoeach logic tile of the plurality of logic tiles in response to a testmode control signal of a test sequence wherein the configuration testdata is written into a plurality of the bitcells of each logic tile ofthe plurality of logic tiles concurrently during the test sequence. 2.The integrated circuit of claim 1 further including: test mode controlcircuitry, electrically connected to each logic tile of the plurality oflogic tiles and configurable to issue the test mode control signal. 3.The integrated circuit of claim 1 further including: test mode controlcircuitry, electrically connected to each logic tile of the plurality oflogic tiles and configurable to issue a control signal wherein, inresponse, circuitry of each logic tile of the plurality of logic tilesundergoes the test sequence concurrently.
 4. The integrated circuit ofclaim 1 wherein: isolation circuitry, connected between the interconnectnetwork of the associated logic tile and the interconnect network ofeach adjacent logic tile, configurable to electrically disconnect theinterconnect network of each logic tile of the plurality of logic tilesfrom the interconnect network of each logic tile of the other logictiles of the plurality of logic tiles.
 5. The integrated circuit ofclaim 1 wherein: the isolation circuitry includes one or moremultiplexers, wherein each multiplexer of the isolation circuitryincludes: (i) a first input connected to a tile-to-tile interconnectproviding an input from the interconnect network of another logic tileof the plurality of logic tiles and (ii) a second input connected to atile-to-tile interconnect providing an output from the interconnectnetwork of the associated logic tile.
 6. The integrated circuit of claim5 further including: test mode control circuitry, electrically connectedto each logic tile of the plurality of logic tiles and configurable toconcurrently issuing one or more control signals to the first isolationcircuitry of each of the logic tiles of the plurality of logic tileswherein, in response, each logic tile of the plurality of logic tiles isin the test mode.
 7. The integrated circuit of claim 1 wherein: theisolation circuitry includes one or more multiplexers, wherein eachmultiplexer of the isolation circuitry includes: (i) a first inputconnected to a tile-to-tile interconnect providing an input from theinterconnect network of another logic tile of the plurality of logictiles, (ii) a second input connected to a tile-to-tile interconnectproviding an output from the interconnect network of the associatedlogic tile and (iii) an output connected to an input of a stage of theinterconnect network of the associated logic tile.
 8. An integratedcircuit comprising: a field programmable gate array including: aplurality of logic tiles, wherein, during operation of the fieldprogrammable gate array, each logic tile is configurable to connect withat least one other logic tile of the plurality of logic tiles, andwherein each logic tile of the plurality of logic tiles includes: anormal operating mode, a test mode, an interconnect network including aplurality of multiplexers, wherein during operation of the fieldprogrammable gate array, the interconnect network of each logic tile isconfigurable to electrically connect with the interconnect network of atleast one other adjacent logic tile of the plurality of logic tiles viaone or more tile-to-tile interconnects in the normal operating mode, andreconfigurable building block I/O logic; and control circuitry,electrically connected to each logic tile of the plurality of logictiles, to enable concurrently writing configuration test data into eachlogic tile of the plurality of logic tiles in response to a test modecontrol signal of a test sequence wherein the configuration test data iswritten into a plurality of reconfigurable building block I/O logic ofeach logic tile of the plurality of logic tiles concurrently during thetest sequence
 9. The integrated circuit of claim 8 further including:isolation circuitry, located at an input to the reconfigurable buildingblock I/O logic of the logic tile, configurable to responsivelydisconnect the input to the reconfigurable building block I/O logic ofthe logic tile from circuitry external to the logic tile in the testmode to thereby electrically disconnect the reconfigurable buildingblock I/O logic from circuitry external to the logic tile in the testmode.
 10. The integrated circuit of claim 9 wherein: the isolationcircuitry includes one or more multiplexers, wherein each multiplexer ofthe isolation circuitry includes: (i) a first input connected tocircuitry external to associated logic tile and (ii) a second inputconnected to an output from the associated reconfigurable building blockI/O logic of the associated logic tile.
 11. The integrated circuit ofclaim 10 wherein: each multiplexer of the second isolation circuitry, inthe test mode, is capable of connecting an output from the associatedreconfigurable building block I/O logic of the associated logic tile toits output.
 12. The integrated circuit of claim 11 further including:test mode control circuitry, configurable to concurrently issue one ormore control signals to the isolation circuitry of each of the logictiles of the plurality of logic tiles wherein, in response, each logictile is in the test mode.
 13. A method of testing an integrated circuitcomprising a field programmable gate array including a plurality oflogic tiles, wherein each logic tile includes (a) bit cells, (b)reconfigurable building block I/O logic, and (c) an interconnect networkhaving a plurality of multiplexers, wherein during a normal operatingmode of the field programmable gate array, the interconnect network ofeach logic tile is configurable to electrically connect with theinterconnect network of at least one other logic tile of the pluralityof logic tiles via one or more tile-to-tile interconnects, the methodcomprising: providing a test mode command to each logic tile of theplurality of logic tiles to configure each logic tile of the pluralityof logic tiles for test, wherein in response, the field programmablegate array is in the test mode; concurrently writing configuration testdata into the bitcells and/or reconfigurable building block I/O logic ofeach logic tile of the plurality of logic tiles when the fieldprogrammable gate array is in the test mode; and after concurrentlywriting configuration test data into bitcells and/or reconfigurablebuilding block I/O logic in each logic tile of the plurality of logictiles, concurrently performing a test sequence on each logic tile of theplurality of logic tiles when the field programmable gate array is inthe test mode.
 14. The method of claim 13 wherein: providing a test modecommand to each logic tile of the plurality of logic tiles includesconcurrently providing the test mode command to each logic tile of theplurality of logic tiles to configure each logic tile of the pluralityof logic tiles for test.
 15. The method of claim 13 further including:reading-back test data from the plurality of logic tiles, (i) when thefield programmable gate array is in the test mode and (ii) beforeperforming the test sequence, to verify the configuration test dataconcurrently written into bitcells and/or reconfigurable building blockI/O logic of each logic tile of the plurality of logic tiles.
 16. Themethod of claim 13 further including: electrically isolating each logictile from the other logic tiles of the plurality of logic tiles when thefield programmable gate array is in a test mode.
 17. The method of claim16 wherein: electrically isolating each logic tile from the other logictiles of the plurality of logic tiles when the field programmable gatearray is in a test mode includes electrically isolating the interconnectnetwork of each logic tile from the interconnect networks of the otherlogic tiles of the plurality of logic tiles.
 18. The method of claim 16wherein: electrically isolating each logic tile from each of the otherlogic tiles of the plurality of logic tiles when the field programmablegate array is in a test mode includes electrically isolating thereconfigurable building block I/O logic of each logic tile from (i)circuitry of other logic tiles of the plurality of logic tiles and/or(ii) circuitry external to each logic tile of the plurality of logictiles.
 19. The method of claim 16 wherein: electrically isolating eachlogic tile from each of the other logic tiles of the plurality of logictiles when the field programmable gate array is in a test mode includeselectrically isolating: the interconnect network of each logic tile fromthe interconnect network of each of the other logic tiles of theplurality of logic tiles, and the reconfigurable building block I/Ologic of each logic tile from (i) circuitry of other logic tiles of theplurality of logic tiles and/or (ii) circuitry external to each logictile of the plurality of logic tiles.
 20. An integrated circuitcomprising: a field programmable gate array including: a plurality oflogic tiles, wherein, during operation of the field programmable gatearray, each logic tile is configurable to connect with at least oneother logic tile of the plurality of logic tiles, and wherein each logictile of the plurality of logic tiles includes: a normal operating mode;a test mode; an interconnect network including a plurality ofmultiplexers, wherein during operation of the field programmable gatearray, the interconnect network of each logic tile is configurable toelectrically connect with the interconnect network of at least one otheradjacent logic tile of the plurality of logic tiles via one or moretile-to-tile interconnects in the normal operating mode; reconfigurablebuilding block I/O logic; and isolation circuitry, located at an inputto the reconfigurable building block I/O logic of the logic tile,configurable to responsively disconnect the input to the reconfigurablebuilding block I/O logic of the logic tile from circuitry external tothe logic tile in the test mode to thereby electrically disconnect thereconfigurable building block I/O logic from circuitry external to thelogic tile in the test mode wherein: the isolation circuitry includesone or more multiplexers, wherein each multiplexer of the isolationcircuitry includes: (i) a first input connected to circuitry external toassociated logic tile and (ii) a second input connected to an outputfrom the associated reconfigurable building block I/O logic of theassociated logic tile.
 21. The integrated circuit of claim 20 wherein:each multiplexer of the isolation circuitry, in the test mode, iscapable of connecting an output from the associated reconfigurablebuilding block I/O logic of the associated logic tile to its output. 22.The integrated circuit of claim 20 further including: test mode controlcircuitry wherein the isolation circuitry is responsive to one or morecontrol signals from the test mode control circuitry.
 23. The integratedcircuit of claim 22 wherein: the test mode control circuitry is capableof concurrently issuing one or more control signals to the isolationcircuitry of each of the logic tiles of the plurality of logic tileswherein, in response, each logic tile is in the test mode.